Image forming devices that do not heat fixing rollers as much as possible are in demand. These image forming devices capable of performing low-temperature fixing are preferable in order to conserve energy and to reduce the size of the devices. Thus, the toner for developing an electrostatic latent image (hereinafter may be referred to as “toner”) is expected to perform low-temperature fixing more effectively. At the same time, it is preferable that the toner does not melt and adhere easily to a heated fixing roller. In other words, a high-temperature offset of the toner is expected to occur at a high temperature (high-temperature offset resistance characteristics). Furthermore, the toner is expected to have excellent properties in heat-resistant preservability.
One way to enhance the low-temperature fixing characteristics of the toner is to lower the glass transition temperature (hereinafter may be referred to as “Tg”) of a binder resin contained in the toner. However, when the glass transition temperature of the binder resin is simply lowered, the heat-resistant preservability of the toner may deteriorate.
According to techniques designed to solve the problems described above, a releasing agent is blended into the toner so that a specific differential scanning calorimetric (hereinafter may be referred to as “DSC”) curve can be obtained from the toner or the releasing agent. Such techniques are disclosed in, for example, Japanese Unexamined Patent Application, First Publication No. H8-334920, Japanese Unexamined Patent Application, First Publication No. H8-278657, Japanese Patent No. 3210245, Japanese Unexamined Patent Application, First Publication No. 2002-323793, and Japanese Unexamined Patent Application, First Publication No. 2002-40706.
However, there is a demand for a toner that has even more excellent fixing properties such as low-temperature fixing characteristics and high-temperature offset resistance characteristics as well as heat-resistant preservability properties.
Therefore, the present invention aims to provide a toner that is excellent in fixing properties such as low-temperature fixing and high- temperature offset resistance as well as in heat-resistant preservability.